The present invention is drawn to an improved inlet valve assembly for use in subsurface sucker rod operated reciprocating piston pumps used in the petroleum industry for pumping oil from a downhole well to the surface.
Typically, subsurface sucker rod operated reciprocating piston pumps comprise a pump barrel having any inlet check valve and an outlet check valve and a pump plunger which is reciprocated within the barrel via a sucker rod. The intake valve is generally located at the entrance to the pump barrel and allows for the flow of well fluids into the pump barrel. The discharge valve is commonly located in the plunger and permits the flow of well fluids out of the pump barrel and up to the surface. Upon reciprocation of the pump plunger by the sucker rod, the coordinated action of both the intake valve and the discharge valve results in fluid flow from the well to the surface.
In order for the reciprocating piston pumps to operate properly they must be anchored within the production tube of the deep well. Thus, during normal pumping operations from the well the reciprocating piston pump is anchored within the production tube. However, during well maintenance, repair and stimulation operations, such as, steam injection or diluent injection, it is necessary to stop the normal pumping operation and to remove the subsurface reciprocating pump from its anchored position in the production tube as no fluids could flow down through the pump when in its anchored position. While the pump must be unanchored in order to carry out fluid injection and the like as aforesaid, it is highly desirable that the reciprocating piston pump remain within the production tube in order to avoid the cost and lost time associated with bringing the subsurface reciprocating pump and sucker rod string to the surface during the aforesaid operations. Accordingly, it is common practice in the prior art to unanchored the subsurface reciprocating pump by pulling the sucker rod string from the surface and move the pump a short distance from its anchored position to an enlarged section of the production tube. In this position, specific fluids from the surface can be injected downhole into the well for maintenance, repair and recovery stimulation.
During the injection of the aforesaid fluids into the well it is extremely important not to allow any flow through the pump barrel of the subsurface reciprocating pump as the fluids being injected generally carry particles which are known to damage the pump plunger and pump barrel surfaces. Accordingly, in existing systems one must choose between removing the reciprocating pump entirely from the production tube or suffer the consequences of passing a portion of the aforesaid injected fluid through the pump barrel of the pump thus resulting in the aforesaid damage to same.
Naturally, it would be highly desirable to provide a system wherein the reciprocating piston pump may be maintained in the production tube of a downhole well and at the same time insure that no fluids which would damage the pump will pass through the pump during the maintenance, repair and stimulation operations as set forth above.
Accordingly, it is the principal object of the present invention to provide an improved inlet valve assembly for use in subsurface sucker rod operated reciprocating piston pumps.
It is a particular object of the present invention to provide an intake valve assembly as aforesaid wherein the inlet valve to the reciprocating piston pump is locked in its closed position when the pump is in its unanchored, non-pumping position within the production tube of a deep well.
It is a further object of the present invention to provide an inlet valve assembly as aforesaid wherein the inlet valve is freely moveable between its open and closed position when anchored within the production tube of the deep well for pumping fluid from the well to the surface.
It is a further object of the present invention to provide an inlet valve assembly as aforesaid which is effective in service and relatively inexpensive to manufacture.
Further objects and advantages of the present invention will appear hereinbelow.